JPH05257403A - Fixing device - Google Patents

Abstract

PURPOSE:To discharge the charge of an electrified fixing roll. CONSTITUTION:A roller shaft 42 of a pressing roller 41 is supported by bearings 50a and 50b and the bearings 50a and 50b are energized upward by springs 43 and 44. The pressing roll 41 is pressed to the heat roll 40 and the pressing roll 41 is rotated following the rotation of the heat roll 40. Top end 43a of the spring 43 is extended and brought into slide-contact with the roller shaft 42. Bottom end of the spring 43 is grounded. The roll shaft 42 is electrified by friction between the roller shaft 42, bearing 50a and 50b. The electrified charge is discharged to the ground through the spring 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus, which removes electric charges charged by rotation of a roller.

[0002]

2. Description of the Related Art As shown in FIG. 7, a conventional fixing device comprises a heat roller 1 having a heater built therein and a pressure roller 2, and a roller shaft 3 of the pressure roller 2 is rotatably supported by bearings 4 and 5. ing. Both bearings 4 and 5 are urged toward the heat roller 1 by springs 6 and 7, and the pressure roller 2 is pressure-bonded to the heat roller 1. Then, as the heat roller 1 rotates, the pressure bonding roller 2 is driven.

At this time, frictional charging occurs between the roller shaft 3 and the bearings 4 and 5 due to the rotation of the pressure roller 2.

Therefore, in order to remove the electric charge charged on the pressure roller 2, a contact rod 8 is incorporated in the bearing 4, one end of the contact rod 8 is brought into contact with the roller shaft 3 of the pressure roller 2, and the other end is removed from the bearing 4. Put it down a little. Then, one copper plate 9 is sandwiched between the spring 6 and the bearing 4, the spring 6 is grounded, and the charge of the pressure roller 2 is released through the contact rod 8 and the spring 6.

[0005]

In the conventional method, it is necessary to incorporate the contact rod 8 into the bearing 4, and it takes time to assemble, and the addition of the contact rod and the copper plate increases the number of parts and increases the cost. I was following.

In view of the above, it is an object of the present invention to provide a fixing device capable of releasing the electric charge of the roller with a small number of parts.

[0007]

As shown in FIGS. 1 and 2, a means for solving the problems according to the present invention comprises a heat roller 40 and a pressure roller 41 pressure-bonded to the heat roller 40, and a roller shaft 42 of the pressure roller 41. Are provided for urging the roller shaft 42 toward the heat roller 40. The roller shaft 42 and the spring 43 are made of a conductive material, and one end of the spring 43 is extended to contact the roller shaft 42. The end is grounded.

[0008]

In the above means for solving the problem, when the pressure roller 41 is rotated by being driven by the heat roller 40, the roller shaft 42 is rotated.
Between the roller shaft 4 and the bearings 50a and 50b due to friction.
2 becomes charged.

However, since the conductive spring 43 is in sliding contact with the roller shaft 42, the electric charge charged on the roller shaft 42 flows through the spring 43 to the ground.

[0010]

FIG. 6 shows a copying machine equipped with a fixing device according to the present invention.
Shown in. In the copying machine according to the present embodiment, a movable document placing table 11 is provided on an upper part of a copying machine body 10, and an original document holding member 13 for pushing an original document 12 placed thereon is provided on the original document placing table 1.
1 is arranged to be openable and closable.

Then, the original placing table 1 of the original pressing member 13
A white mat 14 is attached to the surface facing the No. 1.

In the copying machine main body 10, an irradiation lamp 15 for irradiating the original 12 on the original table 11 and a rod lens array 17 for guiding the reflected light reflected from the original 12 and the original pressing member 13 to the photoconductor 16. A charging device 18 for uniformly charging the surface of the photoconductor 16 rotatably arranged, a developing device 19 for visualizing the electrostatic latent image formed on the photoconductor 16 by reflected light, and a paper feeding device 20. The transfer roller 21 that transfers the toner image on the photoconductor 16 to the transfer paper that is conveyed from the transfer device, the fixing device 22 that fixes the toner image transferred to the transfer paper, and the toner that remains on the photoconductor 16 after the transfer. And a cleaning device 23 for removing.

The developing device 19 comprises a developing tank 25 and a toner replenishing tank 26, and the magnet roller 2 is placed in the developing tank 25.
7 and an agitating roller 28 are internally provided, and a toner replenishing tank 26
Further, a toner replenishing roller 29 and an agitator 30 are internally provided.

The paper feeding device 20 includes a paper feeding roller 32 for feeding the transfer paper from the manual feed tray 31 into the main body, and a registration roller 33.

In the figure, 34 is a cleaning blade, 35 is a toner accommodating portion, 36 is a reflecting plate, S1, S3.
S5 and S6 are paper presence / absence detection sensors, S2 is a toner density sensor, and S4 is a temperature sensor.

Further, the document placing table 11 is moved by a planetary gear which is arranged between endless gears using a rack gear which are connected in a loop shape. When the drive output gear is driven, this planetary gear moves down or up the loop-shaped gear, enabling the endless gear to reciprocate.

The endless gear and the planetary gear have two stages, and allow different document placing table moving speeds during feeding and returning of the document placing table 11.

The fixing device 22 of this embodiment is as shown in FIG.
A heat roller 40 having a heater built therein and a pressure roller 41 pressure-bonded to the heat roller 40 are provided, and springs 43 and 44 for urging a roller shaft 42 of the pressure roller 41 toward the heat roller 40 are provided. ..

The heat roller 40 is an aluminum cylinder coated with polytetrafluoroethylene (PTFE), and the pressure roller 41 is a roller shaft 42 of SUM24-L made of sulfur and sulfur composite free-cutting steel, and a spring. Type Hardness Test Type A JIS. A. A silicone sponge having a hardness of 10 ° is externally fitted.

The roller shaft 45 of the heat roller 40 is a plastic frame 46 fixed to the main body 10 of the copying machine.
Is rotatably supported by bearings 47a and 47b.

A drive gear 48 is externally fitted and fixed to one end of a roller shaft 45 of the heat roller 40, and is rotationally driven by a motor (not shown).

The roller shaft 42 of the pressure roller 41 is rotatably supported by bearings 50a and 50b as shown in FIG. 2, and the bearings 50a and 50b are erected on a support plate 51 of the copying machine main body 10. It is sandwiched between the pieces 52 so as to be vertically movable.

Between the bearings 50a and 50b and the support plate 51, the spring 4 is arranged to urge the bearings 50a and 50b upward.
3,44 are interposed. On the lower surfaces of the bearings 50a and 50b and the upper surface of the support plate 51, a spring positioning protrusion 53 is formed.
a and 53b are formed respectively.

The springs 43 and 44 are piano wires (SWPW).
Is used and has been hooded, and its specifications are: wire diameter 1 mm, outer diameter 8 mm, total number of turns 5.5, effective number of turns 3.5, winding direction right, free height 11.2 mm, load height 7.6 mm. , The load is 3 kgf.

Then, the one spring 43 has a structure shown in FIGS.
As shown in, the upper end 43a is extended to form an upwardly convex arc shape, and the lower end 43b is linearly extended.

Since the upper end 43a of the spring 43 projects outward from the bearing 50a and tries to move upward due to the elastic force,
The pressure roller 41 is in sliding contact with the lower surface of the roller shaft 42.
On the other hand, the lower end 43b of the spring 43 is grounded via the conductive portion of the copying machine body 10.

Next, the operation of the copying machine of this embodiment will be described.

The original 12 placed on the original table 11
Is irradiated by the irradiation lamp 15. The reflected light is exposed to the photoconductor 16 rotatably arranged through the rod lens array 17. With the surface of the photoconductor 16 uniformly charged by the charging device 18, the original 12
An electrostatic latent image is formed on the photoconductor 16 by exposing the reflected light from the.

This electrostatic latent image is developed by the toner supplied from the developing device 19, and the original 12 is placed on the photoconductor 16.
The toner image corresponding to the image is formed. Subsequently, the photoconductor 16 is transferred from the manual feed tray 31 via the registration roller 33.
The sheet is supplied to the sheet, the toner image is transferred onto the sheet by the transfer roller 21, and is conveyed to the fixing device 22.

After the toner image is transferred onto the paper, the toner attached on the transfer roller 21 moves onto the photoconductor 16 by applying a voltage having a polarity opposite to that of the toner to the transfer roller 21. The toner moved from the transfer roller 21 is transferred to the photosensitive member 16
The toner remaining on the top is removed by the cleaning device 23 and is stored in the toner storage portion 35. Further, the surface of the photoconductor 16 is uniformly discharged by the direct light of the irradiation lamp 15.

When the paper is conveyed to the fixing device 22, the heat roller 40 rotates so that the paper passes between the heat roller 40 and the pressure roller 41. The toner image on the paper is heated and pressed by the heat roller 40 and the pressure roller 41 to be fixed on the paper. After that, the paper is ejected.

Here, the pressure roller 41 is the heat roller 4.
When it rotates following 0, the roller shaft 42 and the bearing 50a,
The roller shaft 42 is charged due to the friction with 50b.

However, since the upper end 43a of the conductive spring 43 is in sliding contact with the roller shaft 42, the electric charge charged on the roller shaft 42 flows through the spring 43 to the ground.

Therefore, the electric charge can be released through the spring while eliminating the conventional contact rod and copper plate. As a result, the cost of the spring is increased, but the elimination of two parts and the cutting of the assembling process can reduce the number of parts and the assembling time, resulting in a large cost reduction.

The present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention.

The material of the roller shaft 42 and the spring need not be limited to that of this embodiment.

[0037]

As is apparent from the above description, according to the present invention, one end of the spring for urging the roller shaft of the pressure roller in the direction of the heat roller is extended and brought into contact with the roller shaft.
Since the other end of the spring is grounded, the electric charge generated by the frictional charging due to the rotation of the roller shaft can flow to the ground via the spring.

Therefore, it is not necessary to add a component for releasing charges as in the conventional case, and the number of components and the assembly time can be shortened.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing device showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a front view of the spring.

FIG. 4 is a plan view of a spring.

FIG. 5 is an enlarged view of the upper end portion of the spring.

FIG. 6 is an overall configuration diagram of a copying machine according to the present invention.

FIG. 7 is a configuration diagram of a conventional fixing device.

[Explanation of symbols]

 40 Heat Roller 41 Crimping Roller 42 Roller Shaft 43, 44 Spring

Claims (1)

[Claims] 1. A heat roller and a pressure-bonding roller pressure-bonded to the heat roller are provided, and a spring for urging the roller shaft of the pressure-bonding roller toward the heat roller is provided. The roller shaft and the spring are made of a conductive material. A fixing device in which one end of the spring is extended and brought into contact with the roller shaft, and the other end of the spring is grounded.